Tilting charge well perforating assembly



.B. M. CALDWELL ETAL TILTING CHARGE WELL PERFORATING ASSEMBLY Dec. 11, 1962 Filed Feb. 19, 1954 United rates Patent- 3,057,678 TILTING CHARGE WELL PERFORATING ASEMBLY Blake M. Caldwell and Joe P. Wier, Fort Worth, Tex.,

assignors, by mesne assignments, to Halliburton Company, a corporation of Delaware Filed Feb. 19, 1954, Ser. No. 411,349 '7 Claims. (Cl. 102-26) This invention relates to well perforating assemblies and is particularly concerned with the tiltable mounting of perforating units in an assembly whereby units of greater longitudinal dimension than the diameter of a well tubing may be run into a well through such tubing to be detonated after emergence from the lower end of the tubing at the desired area of the formation.

Oil well drilling by present day modern methods includes the steps of drilling the borehole to the desired formation by the use of a rotary bit to which drilling fluid or mud is supplied during rotation. The drilling mud is customarily circulated down through the drill pipe and discharged from the drill bit to move upwardly in the well bore for the purpose of carrying away the cuttings,

from the bit, supporting the wall of the well, and maintaining a predominant pressure upon the formation to hold back any pressures encountered therein. When the drilling is completed a casing is inserted extending to the bottom of the bore. In order to seal the casing against the bore wall to prevent the flow of connate fluid from one zone to another along the outer surface of the casing and in order to anchor the casing securely in position, cement is pumped downwardly through the casing and therefrom upwardly around the lower end of the same to fill the space between the casing and the well bore. For a long time it has been customary to perforate the casing and its surrounding sheath of cement at the zone where oil flow is contemplated before the well is capped and while the heavy mud is within the casing. A more recent development in the completion of oil wells provides for the running in of the production tubing and the affixing of the well head equipment prior to the perforation so that the heavy drilling mud may be washed from the well prior to the perforation, thus preventing the mud from penetrating the perforated openings and blocking the flow of production fluid.

Prior to the use of this completion method the guns used included fixed horizontally disposed units having a length approaching as far as practical the diameter of the casing so as to attain maximum fire power and this was conventional regardless of whether the unit used shaped charges of explosive material or guns which fired perforating bullets. Such guns were, of course, impossible of use where the production tubing is already in place since the internal diameter of the tubing is less than the length of the unit. Guns having a maximum diameter small enough to be accommodated by the internal diameter of the tubing do not have adequate firing power to pierce the casing and cement sheath and sufficiently penetrate the formation.

It has been suggested that an assembly be provided in which units of adequate length, exceeding the diameter of the production tubing, are pivotally mounted in a carrier, the units being disposed in vertical alignment with the axis thereof as they are lowered through the tubing and being restrained in such position by engagement with the inner face of the tubing. The units are pivoted below their center of gravity to drop to horizontal firing position with their axes normal to the axis of the carrier after emergence from the lower end of the tubing. Such a device is disclosed in the W. H. Thompson et al. Patent 2,543,814, with respect to which the present invention is an improvement.

ice

In the Thompson device no provision is made for a retraction of the unit after emergence from the bottom of the tubing. While normally the charges will be detonated after they emerge below the tubing, and the carrier destroyed with the firing of the charges, it is possible that withdrawal of the assembly may be desirable for any one of various reasons. Where the normal position of the charge, when free of the tubing, is horizontal with both ends extending beyond the projection of the tubing diameter, re-entry with the units in such position is impossible. Another problem which may occur in the use of the device of the Thompson patent is the hanging up of the assembly by engagement of the charge units at the coupling area between tubing sections. In the Thompson structure the units are so pivoted as to tend to drop to horizontal posi tion by gravity and thus the ends of the units continuously drag the tubing surface and may engage between the spaced tubing ends. Such engagement may result in preventing further lowering and in efforts to disengage the carrier it may become broken or damaged. By like or similar occurrence the flexible restraining means used to preclude dropping of the units below a horizontal position may be damaged or broken in which case the desired horizontal position of the charge after emergence will not be achieved. It is also possible that mud, rust or accident may prevent the free pivotal movement, under gravity, of the units to horizontal position.

With these and other problems in mind it is among the objects of the present invention to provide a novel and improved perforating assembly providing for the lowering of perforating units of greater length than the diameter of a well tubing through such tubing and to a location therebelow wherein such charges may be disposed in horizontal position.

More specifically it is among the objects of the present invention to provide a device of the character set forth which permits the re-entry of the device, with its charges, at the bottom of the tubing through which they are lowered after they have emerged therefrom.

As a corollary to the above object it is a further object to provide means for returning the perforating units to axial alignment with their carrier after they have been moved from such position to one in which their axes lie normal to the axis of the carrier as an incident to their emergence from the lower end of the tubing.

Another object of the invention is to provide a device of the character described including means for moving the charge units to horizontal position by resilient means restrained against action during passage of the gun through a well tubing and acting upon emergence of the unit from the tubing to dispose the same in horizontal position.

A further object of the invention is to provide a perforating assembly including means for guiding the units as they are lowered through the well. tubing to preclude engagement thereof with recesses or projections of the internal wall of the tubing whereby they might be hung up or injured during the lowering operation.

It is also an object of the invention to provide a novel and improved pivotal mounting for the units and an actuating means therefor so that the charge may be moved to horizontal position after emergence from the tubing without dependance upon gravity.

Other objects of the invention include the provision of a novel and improved carrier for perforating units which carrier is formed of sections arranged for end to end assembly to permit the fabrication therefrom of a carrier of various required lengths.

These and other objects and features and advantages of the present invention will be apparent from a cons deration of the following specification taken in conjunction with the accompanying drawings in which:

FIGURE 1 is a fragmentary vertical section of a well bore showing the tubing disposed therein and the assembly of the present invention emerging through the lower end of such tubing;

FIGURE 2 is an enlarged fragmentary view partly in section illustrating the charges after emergence from the u i and FIGURE 3 is a horizontal, sectional view taken on the line 33 of FIGURE 2.

In general the present preferred form of the invention may be defined as comprising a series of perforating units pivotally mounted in longitudinal spaced relation in a carrier which comprises a successive series of carrier rings joined by pairs of parallel side bars between and to which the units are pivotally mounted. An important feature of the invention is the suspension of the units at an intermediate point such that upon pivotal movement the upper end will clear the rings but will not protrude beyond the projected diameter of the tubing. Thus the unit may swing freely both from and to the vertical position, the latter being effected by engagement of the opposite protruding portion of the unit with the tubing end. In this respect, the pivotal axis on which the unit is mounted is adjacent the non-firing end of the unit and within a distance therefrom not greater than the radius of the carrier. The successive pairs of side bars are angularly spaced so as to provide angularly related axes for pivotal movement of the successive adjacent units. Each unit is spring biased to horizontal position at which position it is restrained from further pivotal movement by the engagement of the side wall thereof, or preferably a projection formed thereon, with the lower side of the ring next above. The spring biasing is provided by individual coil springs extending from the ring next below each unit to the top of the unit above its pivotal point. Such springs are held under tension and the units are restrained in their parallel position with respect to the carrier axis and against pivotal movement under the influence of the biasing spring during movement of the carrier through the tubing by engagement of the lower ends thereof with the internal walls of the tubing. A side projection mounted on the unit preferably at the end farthest from its pivotal mounting and having rounded projecting portions engages the side wall of the tubing as the gun is moved therethrough and acts to cam the body of the unit away from projecting shoulders such as may be encountered at the tubing couplings thus precludes damage or hanging up of the carrier as the same is lowered through the tubing. The projection also acts as a camming means for returning the units to vertical position should the carrier be drawn upwardly through the lower end of the tubing in the event that the units are not discharged after lowering through said opening. The invention also provides simple and effective firing means in the form of a priming cord which is threaded through suitable retaining means on the units so that detonation of the successive units may occur as the priming cord burns.

Referring now more particularly to FIGURE 1 of the drawings the numeral indicates the conventional cement sheath disposed between a wellbore casing 11 and the formation 12. It will be understood that in the completion method above referred to the casing 11 is lowered into the wellbore in the formation 12 after drilling and that cement in the form of slurry is forced upwardly around the casing to set in the manner shown. The production tubing formed of a series of tubing lengths 14 threadedly interengaged by couplings 15 is lowered into the well to a point just above that at which the well is to be produced and the well head equipment is applied. The drilling mud may then be washed from the well and the casing is ready to be perforated.

The carrier of the present form of the invention comprises a series of spaced annular carrier rings 16 provided with a series of circumferentially spaced equidistant peripheral recesses 17 comprising individual pairs of recesses. The recesses of each pair are diametrically opposed and receive the ends of vertical side bars 18 extending between, and joining in spaced relation, adjacent rings 16. Securement of the ends of the bars 18 in the recesses 17 of the rings 16 is by way of countersunk screws 19. As will be noted from the drawings, the separate pairs of recesses receive the upper and lower ends of the bars 18 the lower end of one pair of side bars are received in one pair of oppositely disposed recesses and the upper end of another pair of side bars are received in the opposite recesses of the other pair. In this manner it will be seen that successive pairs of side bars are disposed in vertical planes angularly spaced from each other' As will be hereinafter noted this disclosed arrangement provides for the mounting of the charges on successive axes having 90 angularity. By mounting every other unit for pivotal movement in an opposite direction the perforation pattern may form a spiral, each perforation being equally spaced longitudinally and at a radial angularity of 90 in a uniform direction from the preceding perforation. However the invention is not limited to an assembly which produces such a perforation pattern. Should a different angular relation be desired the pairs of recesses 17 in the rings 16 may have a smaller angular relation and hence the angular relation between units and their resultant perforations may be selected at will.

Each side bar 18 is formed with a trunnion receiving aperture 2t} spaced downwardly from its upper supporting ring 16 the apertures of each pair of bars being coaxial to form a pair of opposed bearings for trunnion pintles 21 of the generally cylindrical perforating units generally indicated by the numeral 22. From this arrangement it will be seen that, as suggested above, the pivotal mounting of the units 22 provides angularly related axes so that when disposed in a horizontal plane and detonated the units will produce the spiral perforation pattern mentioned.

While the perforating units 22 may be of various types and designs as conventionally employed for the firing of perforating bullets or the discharge of a penetrating jet the units here shown by way of illustration are of the latter type.

As more clearly shown in FIGURE 2 each unit comprises a substantially cylindrical casing or shell 23 having an integrally formed rounded lower, outer or firing end 24. Inwardly spaced from the inner surface of the end 24 the shell is formed with a shoulder 25 which receives thereagainst the outer edge of an inverted conical liner 26 behind which the charge forming explosive 27 is packed and by which the explosive is shaped to produce, upon detonation, the desired perforating jet. Since both bullet firing units and jet units here depicted are both well-known in the present art and since the present invention is not concerned with the structural details of either, further discussion thereof is not deemed herein required. It will be understood, however, that the shell 23 is preferably formed of destructible material such as aluminum so that upon detonation of the charge the casing will be wholly disintegrated without leaving debris which might otherwise encumber the free flow of fluid when the Well is produced. Opposite the end 24 the shell is closed by a circular head 28 under which the explosive detonating arrangement is located. Externally the head 28 is provided with a priming cord clip 29 secured by screws 30 and by which the priming cord 31 is held against the head so that as the cord burns past the head the explosive 27 will be detonated.

An important feature of the invention is the fact that the diameter of the head 28 in relation to the pivotal axis of the shell 23 is such that the edge of the head may move in an arcuate path within the ring 16 and the arrangement is such that when the unit is in full horizontal position as shown in FIGURE 2 the head end of the unit does not protrude beyond a projection of the internal area of the tubing 14. Thus when the unit is moved upwardly with the carrier for re-entry into the tubing the head may swing back to the vertical position without striking the lower edge of the tubing or being blocked against such pivotal movement. The opposite or firing end of the shell does project beyond a projection of the tubing area and upon retracting movement the end of the tubing strikes the projecting firing end so as to move the unit pivotally back to its original position against the tension of the spring with its axis substantially coincident with the axis of the tubing. In such movement a projecting fin 32 extending from the side of the shell 21 in a plane normal to the plane of the pivotal axis of the shell will engage the lower edge of the tubing to accomplish such movement. The fin 32 also acts as a stop to engage the lower face of the ring 16 next above the unit so as to insure proper horizontal location of the unit after it emerges from the tubing.

It will be seen of course that since the units are pivoted adjacent the heads 28 thereof they will tend to assume the vertical position; however while such mounting would tend to maintain the units coaxially with the tubing as they pass therethrough they would tend to retain this vertical position on emergence. Therefore a coil spring 33 is provided extending from one of the screws 19 of the ring next below each unit and therefrom to a spring connecting arm 34 formed as a return bent extension of the clip 29. As noted from FIGURE 1 the springs 33 are under tension as the assembly passes through the tubing the tension tending to bias the units to pivotal movement with their axes normal to the axis of the tubing. Such movement is restrained while the assembly is in the tubing by the engagement of the fin 32 with the wall of the tubing opposite the spring 33. Upon emergence the spring will act to tilt the unit to the horizontal position as shown in FIGURE 2. It will be noted that the rounded contour of the fin 32 is such as to guide the lower end of the unit through coupling members 15 and that the arrangement avoids any danger of damage to the unit or hanging up of the assembly.

Although the resilient biasing means shown and described herein are of the coiled tension spring type, it will be understood that other forms of biasing means, such for example as torsion springs, may be employed if desired.

From the foregoing it willbe seen that in the use of the assembly as the carrier is lowered through. the tubing 14 the-units are retained in vertical position against the tension of the spring 33 and with their axes in alignment with the axis of the carrier by engagement of the fins 32 with the walls of the tubing. As the units successively emerge from the bottom of the tubing the springs 33 tilt the units to the horizontal position shown, the upper end of thefin 32 acting as astop by engaging the lower face of the ring 16 above each unit. Upon emergence of all the units they may be detonated successively by the burning of the priming cord 31. Should it be desired to retract the assembly before firing, or in the event of a misfire, upward movement of the carrier will cause the successive units to have their fins 32 engaged by the lower end of the tubing, thus applying counterrotation against the tension of the spring 33 to restore the units to vertical position whereby the assembly may freely move upwardly in the tubing.

As herein indicated the present invention is not limited to the specific structural details and arrangements herein shown and numerous changes, modifications and full use of equivalents may be resorted to in the practice of the invention without departure from the spirit or scope of the appended claims.

We claim:

1. An assembly for perforating wells below tubing suspended therein comprising: a vertical carrier including a plurality of longitudinally spaced rings and angularly displaced diametrically opposite pairs of side bars interconnecting said rings; perforating units each having a head end and a firing end and having a length exceeding and a diameter less than the diameter of said rings, each pivotally mounted on a pair of said side bars between said side bars and said rings on a transverse axis adjacent the head end of each said unit and within a distance therefrom not greater than the radius of said rings, each said unit being retained in, vertical disposition within said carrier with its firing end directed downwardly; resilient means urging each said unit to pivot from said vertical disposition upon emergence of said unit from the lower end of said tubing to assume a firing position in which each said unit is disposed at a substantial angle to the vertical with said firing end projecting substantially outside of said rings and a portion of said unit abutting a superjacent one of said rings and with said head end inside of said longitudinally spaced rings; each unit upon withdrawal into said tubing being cammed back to said vertical disposition against the urgence of said resilient means by engagement of the projecting firing end of said unit with the lower end of the tubing whereby the firing end is again directed downwardly; and means for firing said perforating units.

2. An assembly for perforating wells below tubing suspended therein comprising: a vertical carrier including a plurality of longitudinally spaced rings and angularly displaced diametrically opposite pairs of side bars interconnecting said rings; perforating units each having a head end and a firing end and having a length exceeding and a diameter less than the diameter of said rings, each pivotally mounted on a pair of said side bars between said side bars and said rings on a transverse axis adjacent the head end of each said unit and within a distance therefrom not greater than the radius of said rings, each said unit being retained in vertical disposition within said carrier with its firing end directed downwardly; resilient means urging each said unit to pivot from said vertical disposition to abutting engagement with its upwardly adjacent ring upon emergence of said unit from the lower end of said tubing to assume a firing position in which each said unit is disposed substantially at right angles to the vertical with said firing end projecting substantially outside of said rings and a portion of said unit abuttingrsaid upwardly adjacent ring and with said head end inside of said longitudinally spaced rings; each unit upon withdrawal into said tubing being cammed back to said vertical disposition against the urgence of said resilient means by engagement of the projecting firing end of said unit with the lower end of the tubing whereby the firing end is again directed downwardly; and means for firing said perforating units.

3. An assembly for perforating wells below tubing suspended therein comprising: a vertical, elongate carrier; a perforating unit having a head end and a firing end opposite said head end and having a length exceeding and a diameter less than the width of said carrier pivotally mounted within said carrier on a transverse axis adjacent said head end, said unit being retained in running position in vertical disposition within said carrier with said firing end directed downwardly and pivotable on said axis to firing position in which said unit is disposed at a substantial angle to the vertical with said firing end projecting substantially outside of said carrier, said axis being located to provide containment of said head end within said carrier as said unit is pivoted between said running position and said firing position; resilient means urging said unit to pivot from said running position to said firing position; and stop means on said carrier engageable by said unit to prevent pivotal movement of said unit beyond said firing position; said unit upon withdrawal into said tubing being cammed from said firing position to said running position against the urgence of said resilient means by engagement of the projecting firing end of said unit with the lower end of said tubing.

4. An assembly for perforating wells below tubing suspended therein comprising: a vertical, elongate carrier; a perforating unit having a head end and a firing end opposite said head end and having a length exceeding and a diameter less than the width of said carrier pivotally mounted within said carrier on a transverse axis adjacent said head end, said unit being retained in running position in vertical disposition within said carrier with said firing end directed downwardly and pivotable on said axis to firing position in which said unit is disposed at a substantial angle to the vertical with said firing end projecting substantially outside of said carrier, said axis being located to provide containment of said head end within said carrier as said unit is pivoted between said running position and said firing position, said unit having a. fin projecting upwardly therefrom when the unit is in firing position, said fin extending outwardly from said carrier to the outer extremity of said firing end; resilient means urging said unit to pivot from said running position to said firing position; and stop means on said carrier engageable by said unit to prevent pivotal movement of said unit beyond said firing position; said unit upon with drawal into said tubing being cammed from said firing position to said running position against the urgence of said resilient means by engagement of said fin with the lower end of said tubing, and said unit being retained in said running position within said tubing by engagement of said fin with the inner wall of the tubing.

5. An assembly for perforating wells below tubing suspended therein comprising: a vertical, elongate, cylindrical carrier; a perforating unit having a head end and a firing end opposite said head end and having a length exceeding and a diameter less than the diameter of said carrier pivotally mounted within said carrier on a transverse axis adjacent said head end and within a distance therefrom not greater than the radius of said carrier, said unit being retained in running position in vertical disposition within said carrier with said firing end directed downwardly and pivotable on said axis to firing position in which said unit is disposed substantially horizontally with said firing end projecting substantially outside of said carrier; resilient means urging said unit to pivot from said running position to said firing position; and stop means on said carrier engageable by said unit to prevent pivotal movement of said unit beyond said firing position; said unit upon withdrawal into said tubing being cammed from said firing position to said running position against the urgence of said resilient means by engagement of the projecting firing end of said unit with the lower end of said tubing.

6. An assembly for perforating wells below tubings suspended therein comprising: a vertical, elongate carrier; a perforating unit having a head end and a firing end opposite said head end and having a length exceeding and a diameter less than the width of said carrier pivotally mounted within said carrier on a transverse axis adjacent said head end, said unit being retained in running position in vertical disposition within said carrier by said tubing with said firing end directed downwardly and pivotable on said axis to firing position in which said unit is disposed at a substantial angle to the vertical with said firing end projecting substantially outside of said carrier, said axis being located to provide containment of said head end within said carrier as said unit is pivoted between said running position and said firing position; resilient means urging said unit to pivot from said running position to said firing position upon emergence of said unit from the lower end of said tubing; and stop means on said carrier engageable by said unit to prevent pivotal movement of said unit beyond said firing position; said unit upon withdrawal into said tubing being cammed from said firing position to said running position against the urgence of said resilient means by engagement of the projecting firing end of said unit with the lower end of said tubing.

7. An assembly for perforating wells below tubing suspended therein comprising: a vertical, elongate, cylindrical carrier; at perforating unit having a head end and a firing end opposite said head end and having a length exceeding and a diameter less than the diameter of said carrier pivotally mounted within said carrier on a trans- Verse axis adjacent said head end and within a distance therefrom not greater than the radius of said carrier, said unit being retained in running position in vertical disposition within said carrier by sai'dtubing' with said firng end directed downwardly and pivotable on said axis to firing position in which said unit is disposed substantially horizontally with said firing end projecting substantially outside of said carrier; resilient means urging said unit to pivot from said running position to said firing position upon emergence of said unit from the lower end of said tubing; and stop means on said carrier engageable by said unit to prevent pivotal movement of said unit beyond said firing position; said unit upon withdrawal into said tubing being carnmed from said firing position to said running position against the urgence of said resilient means by engagement of the projecting firing end of said unit with the lower end of said tubing.

References Cited in the file of this patent UNITED STATES PATENTS France Mar. 11, 1953 "Jam m e 

